Just called Matrox Tech Support about Ubuntu 10.04 - 64 bit with Matrox Cards.

(For P690 on 64 bit Ubuntu 10.04)

Tech Support says: "At present time there is no support for Ubuntu 10.04."No information could be provided by Tech Support with regards to if or when support may be there, as drivers are provided by a different department. When it is available, it will be announced on Matrox website.